A couple from Arizona was left stunned after discovering more than 5,000 fentanyl pills inside a toy they bought from a thrift store.

On Saturday, Phoenix police said that the couple bought a Glo Worm plush in El Mirage, Arizona for their daughter.

The parents decided to clean and wash the toy before letting their daughter play with it, but found the dangerous pills stashed inside it instead.

“They called #phoenixpolice and gave the dangerous drugs to officers,” the police said via Twitter.

“Remember to inspect all opened and used items.”

Several Twitter users expressed their relief that the parents had inspected the toy before letting their child play with it – a decision that led to the appalling discovery.

“How scary. Imagine a child ingesting just a small amount of that,” one Twitter user wrote.

“Holy Crap,thank God they found this before that baby/or any other child played with that,” wrote another.

Fentanyl, a synthetic opioid often mixed with other illicit drugs like heroin and cocaine, was dubbed as the most dangerous drug in the US.

Prescribed by doctors to treat severe pain, the drug is known to be 50 to 100 times more potent than morphine, and causes euphoric-like effects like heroin.

According to the Centers for Disease Control and Prevention, overdose deaths involving synthetic opioids increased over 16 percent from 2018 to 2019.

Along with OxyContin and Vicodin, Fentanyl is considered a serious contributor to the country’s “opioid epidemic.”

This is not the first time an innocent child’s plaything was used as a vessel for drugs.

In 2015, a mother from New Jersey ordered her daughter a $500, “handmade” mermaid baby doll filled with two bags of cocaine from Etsy.

Further investigation revealed that the Etsy shop based in Alabama had been using the mer-baby dolls as a front for smuggling drugs.